Rotary drum for concrete mixers



Feb. 14, 1950 w, MULLER 2,497,736

ROTARY DRUM FOR CONCRETE MIXERS Filed June 2, 1948 2 Sheets-Sheet l INVENTOR.

55 5 5 7 BA/m m.

Feb. 14, 1950 w. MULLER 2,497,736

ROTARY DRUM FOR CONCRETE MIXERS Filed June 2, 1948 2 Sheets-Sheet 2 I N VEN TOR.

Patented Feb. 14, 1950 UNITED STATES PATENT OFFICE ROTARY DRUM FOR CONCRETE MIXERS Walter Muller, Dunellen, N. J. Application June 2, 1948, Serial No. 30,591

6 Claims. (Cl. 259-17 5') The invention relates primarily to improvements in concrete mixers, in which the concrete is mixed in a rotary drum, but it is adaptable to other uses and purposes.

One of the objects of this invention is to provide a drum concrete mixer which is simple in construction and inexpensive to manufacture yet is very durable and requires a minimum of repair and servicing.

Another object is to provide a concrete mixer which is reenforced at the particular points where it receives the greatest stress and strain, and where accurate form and alignment is necessary.

Another object is to provide a concrete mixing drum whose revolving drum is free'from weave or other irregular movement thus avoiding wear on parts.

Still another object of the invention is to provide a concrete mixer whose drum and drive may be aligned and realigned accurately to give the highest efficiency or to compensate for wear on the parts for use.

Heretofore it has been the practice to construct concrete mixers with a track or guide secured around its periphery, designed to travel in a groove or slot or some equivalent thereof, for the purpose of maintaining the mixing drum in alignment with other parts. a circular track around the outer periphery of the mixing drum or the like is a costly provision. and one which must be accurately constructed and applied, and with great care, or the drum will become misaligned by reason of any slight misalignment of the track. The present invention eliminates the necessity of a track altogether.

It has also been the practice heretofore to form the ends of the mixing drums by bending the ends of the drum inwardly to make such end construction. This inward bend leaves a section of the drum at each end in more or less attenuated condition, the metal being thinner at these points than at any other point on the drum. Since it is common practice to locate idler rollers at the ends of the drum, for the purpose of sta bility, this means that the greatest strain on the mixing drum is placed on its weakest parts. The present invention, however, has for one of its objects the construction of a drum whose strongest point is the point of contact with such idler rollers.

Further objects and advantages will be apparent from the following specification and the The alignment of Fig. 2 is a longitudinal vertical section of the rotary drum mounted on the chassis.

Fig 3 is a vertical medial cross section of the mixer and chassis.

Referring to the drawings, 1 represents the concrete mixing drum which has welded or otherwise secured around exterior at its medial portion an annular rack gear 2 which is in mesh with a drive pinion 3 affixed to the drive shaft 4. The drive shaft 4 is rotated by a suitable motor or sprocket drive such as is commonly used in the art and is not shown in the drawings.

The drum l rests upon eight carrying rollers 5 and 5, near each end thereof and in spaced sets of four each, which are preferably made of rubber or other suitable resilient material. These sets of rollers are rigidl affixed to shafts B, 6 respectively mounted in bearing housings I, I which are secured to the mixer frame member 8, so that the rollers 5 and 5 and the accompanying shafts 6, .6 may rotate freely. On each of the shafts 6, B and centrally thereof, is located a guide roller consisting of a body portion 9 having drilled into it a threaded orifice l0 which receives a set screw H. The body portion 9 is slightly greater in width than the width of the gear 2 and terminates in annular flanges l2 and I2 preferably integral therewith. These flanges l2 and I2 overlap the sides of the gear 2, and perform a function which will be explained later.

Referring to Fig. 3, it will be noted that the drum l is manufactured by forming a cylinder l3 and end members l4 and i5 therefor having the usual central charge and discharge openings 2.0 and 2|. Each of these end pieces has an elongated or deep flange l4 and I5, respectively,

which is welded or otherwise firmly united with the cylindrical section l3 at l6, l1, l8 and 19, so that the thickness of the metal at the zone where the rollers 5 and 5' support the weight of the mixing drum I, and its contents, is doubled, thereby giving extra strength at the point of greater strain.

The purpose of the set screws l l and the guide roller consisting of the body portion 9, with tapped hole l0 and flanges l2, I2, is to provide a means whereby the drum 1 may be adjusted and aligned so that the gear 2 and the pinion gear 3 ma be placedv in exact meshing alignment. Should these gears through use and wear become disaligned, the set screw l I may be loosened and the drum I moved longitudinally until the gears 2 and 3 are again in perfect alignment and register, whereupon the set screw ll may be tightened to secure and preserve the adjustment. In operation, as the drum l rotates under the drive of the pinion 3 acting upon the peripheral the drum l, and positively maintaining the alignment of the gears 2 and 3.

The annular rack and pinion need not be provided with teeth or be of metallic material, and

one or both of the idler shafts may be driven. In this case, the pinion may be omitted. The

grooved positioning rollers or one of them, may

also be toothed to mesh with the annular gear or rack to drive the drum.

Other modifications of the details of construction described and shown, may be made without departing from the scope of the improvements.

What I claim is:

1. In a device of the character described, a frame, drum supporting idler rollers, shafts on which said rollers are secured on said frame, bearings for said shafts in said frame, a mixing drum mounted for rotation on said idler rollers, said drum comprising a cylindrical portion and members at the ends of said :portion partly closing it overlapping said ends and united therewith to form a reenforced shell at the zone of contact of said idler rollers therewith, a medial rotational drive gear extending around the periphery of said drum, a positioning idler roller adjustably secured on one of said shafts between said drum support ng rollers and adapted to engage said gear, said gear adapted also to engage drive mechanism for rotation of said drum.

2. In a device of the character described, a frame, drum supporting idler rollers, shafts on which said rollers are secured on said frame, bearings for said shafts in said frame, a mixing drum mounted for rotation on said idler rollers, said drum comprising a cylindrical portion and members at the ends of said portion partly closing it overlapping said ends and united therewith to form a reenforced shell at the zone ofv contact of said idler rollers therewith, a medial rotational drive gear extending around the periphery of said drum, a positioning idler roller adjustably secured on one of said shafts between said drum supporting rollers and adapted to engage said gear, said gear adapted also to engage drive mechanism for rotation of said drum, comprising adriving pinion engaging said gear and means for driving said pinion.

3. In a device of the character described, a frame, drum supporting idler rollers, shafts on which said rollers are secured on said frame, bearings for said shafts in said frame, a mixing drum mounted for rotation on said idler rol1ers,-

said drum comprising a cylindrical portion and members at the ends of said portion partly clos- 66 ing it overlapping said ends and united therewith to form a reenforced shell at the zone of contact of said idler rollers therewith, a medial rotational drive gear extending around the pe-' riphery of said drum, positioning idler rollers ad justably secured on at least one of said shafts between said drum supporting rollers, and having a recessed periphery receiving said gear, said gear adapted also to engage drive mechanism for rotation of said drum.

4 In a device of the'character described, a

frame, drum supporting idler rollers, shafts on which said rollers are secured on said frame, bearings for said shafts in said frame, a mixing drum mounted for rotation on said idler rollers, said drum comprising a cylindrical portion and members at the ends of said portion partly closing it overlapping said ends and united therewith to form a reenforced shell at the zone of contact of said idler rollers therewith, a medial rotational drive gear extending around the periphery of said drum, positioning idler rollers adjustably secured on said shafts between said drum supporting rollers and adapted to engage said gear, said gear adapted also to engage drive mechanism for rotation of said drum, comprising a driving pinion spaced circumferentially of said drum from said idler rollers and their shaft engaging said gear and means for driving said pinion.

5. In a device of the character described, a frame, drum supporting idler rollers, shafts on which said rollers are secured on said frame, bearings for said shafts in said frame, a mixing drum mounted for rotation on said idler rollers a medial rotational drive gear extending around the periphery of said drum, a positioning idler roller adjustably secured on one of said shafts between said drum supporting rollers and adapted to engage said gear, and having a recessed periphery receiving said gear, said gear adapted also to engage drive mechanism for rotation of said drum, said positioning idler roller being releasably se-' cured on said shaft, and means for releasing and securing it at different positions longitudinally of the shaft to align and realign said gear and pinion.

6. In a device of the character described, a frame, four pairs of drum supporting idler rollers two of said pairs being positioned near each end of said frame and spaced apart, shafts on said frame on which said rollers are secured, two pairs on each shaft, bearings for said shafts in said frame, a mixing drum mounted for rotation on said idler rollers, said drum comprising a cylindrical portion and members at the ends of said portion partly closing it overlapping said ends said gear adapted also to engage drive mechanism for rotation of said drum comprising a driving pinion spaced from said positioning rollers circumferentially of said drum.

WALTER MULLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

